An internal combustion engine has been known that deactivates cylinders by stopping an opening and closing action of intake valves in some of the cylinders and maintaining a valve closing state during an engine operation, that is, performs cylinder deactivation.
When an internal combustion engine returns from a cylinder deactivation mode to an all-cylinder operation mode, torque fluctuation due to a change in the engine output is easily caused.
Therefore, for example, the internal combustion engine described in Patent Document 1 reduces the lift amount of intake valves at the time of returning from the cylinder deactivation mode to decrease the engine output, thereby suppressing generation of the torque fluctuation due to an increase in the engine output when the engine returns from the cylinder deactivation mode to the all-cylinder operation mode.